Arctic sea ice has reached record low levels over the past few years due to climate change. A warming Earth has caused the extent of Arctic sea ice to decrease rapidly, suggesting that the Arctic will in fact be ice free within the next few decades.

In the Antarctic however, there’s a completely different story.

In recent years, the amount of sea ice surrounding Antarctica has expanded, reaching its maximum extent in 2012. How can we reconcile this picture with that of climate change? Well it turns out that they may be related after all. 

A paper has recently been published in the journal Nature Geoscience, which suggests that the growth in Antarctic sea ice may be caused by melting of the Antarctic ice shelves.

The Antarctic continent is actually below sea level in many places, due to the isostatic effects of the large ice sheet, which sits over the continent. This means that the base of some ice sheets are also below sea level, making them vulnerable to melting from below.

As the ice shelves below the water melt, they release a cool, fresh plume of water. Because this water is less dense than the warmer salt water surrounding it, it rises to the surface and freezes into sea ice.

The authors suggest that this process may account for a large proportion of the observed increase in Antarctic sea ice, with the interaction between wind and sea ice likely responsible for the remainder.

If you have access to a subscription for Nature Geoscience, you can access the full article here. Otherwise, you can check out the Nature press release, or the BBCs news story on the article